July, 2011:

New York City Mayor Michael Bloomberg said he will donate $50 million to the Sierra Club, an environmental advocacy group, to promote the organization’s fight against coal-fired power plants.

Mr. Bloomberg announced the gift, which will be spread over four years, at a GenOn coal plant in Alexandria, Va., just outside of Washington, on Thursday.

“Ending coal power production is the right thing to do,” Mr. Bloomberg said. “Because while it may seem to be an inexpensive energy source the impact on our environment and the impact on public health is significant.”

Bruce Nilles, a Sierra Club official, said Mr. Bloomberg had expressed frustration with what he saw as a Congress slow to take action on issues surrounding climate change.

“As the mayor described, he’s been very concerned, as have we, that Congress has been dithering on issues like clean energy and global warming,” Mr. Nilles said. “A big reason he’s making his investment in the Sierra Club is that it brings together his belief that the way to make progress in the United States is issue by issue, community by community.”

Mr. Nilles said the money “gives us an enormous opportunity to be working in literally hundreds of communities across the U.S., helping them make the transition from coal to clean energy.” The gift, he said, will allow the organization to expand its campaign to around 45 states from 15.

Mr. Bloomberg received praise from his New Jersey neighbor, Democratic Sen. Robert Menendez.

“It is wonderful that he has the wherewithal and the wisdom to help Sierra Club combat climate change and clean up the air that New Jerseyans and New Yorkers breathe,” Mr. Menendez said.

Carol Raulston, a spokeswoman for the National Mining Association, suggested Mr. Bloomberg is making a mistake. She criticized the Sierra Club’s strategy to promote clean energy, and said that by taking coal off the table, the organization aims to take away the most affordable electricity in the country. Instead, she said, the Sierra Club should focus on promoting advanced technologies for coal-based electricity.

“The Sierra Club gets sizable donations from a lot of very wealthy Americans who don’t really understand the circumstances of people less fortunate than they, who worry about paying electricity bills,” Ms. Raulston said. “There would have been more productive ways for the mayor to donate his money to address greenhouse gas emissions, but it’s his money.”